The present invention relates to a system for transmitting an ignition signal from a single detonator to a plurality of transmission lines connected to other detonators for the purpose of producing a predetermined, timed blasting pattern. In particular, the present invention relates to a system for controlling the ignition of a series of non-electrical detonators.
In non-electrical detonation of explosives, signals are transmitted between lengths of detonator cord, known as xe2x80x9cshock tubes,xe2x80x9d by employing connector blocks. A connector block typically includes a detonator receiving the detonation signal from its own shock tube, a housing to contain the explosive effect of the detonator and limit the production of shrapnel, and a mechanism for securing a plurality of shock tubes adjacent the charge within the detonator. Upon ignition of the charge within the detonator, signals are generated within the shock tubes held with the securing mechanism. Examples of conventional detonator blocks include those described in U.S. Pat. No. 5,171,935, U.S. Pat. No. 5,204,492, U.S. Pat. No. 5,423,263, U.S. Pat. No. 5,458,611, and U.S. Pat. No. 5,499,581, U.S. Pat. No. 5,703,319, and U.S. Pat. No. 5,792,975, which are incorporated herein by reference.
Conventional shock tube connector systems are limited in a number of ways. For example, they generally can hold a maximum of four to six shock tubes, which limits the number of circuits that can be initiated from a given connector block. Moreover, most connector blocks create a variety of spatial relationships between the explosive charge within the detonator and the several shock tubes held by the block, which often results in inconsistent signal transmission to the individual shock tubes. In addition, to the extent more powerfull detonator charges are employed to ensure adequate signal transmission to all shock tubes, not only does the cost of the system increase, but increased shrapnel may result.
It is the intention of this invention to provide a connector block that can hold up to eight shock tubes and effect signal transmission between the detonator and all eight shock tubes.
It also is the intention of this invention to provide a shock tube connector system that utilizes a modified detonator to transmit detonation signals efficiently and consistently to a plurality of shock tubes.
Additional advantages of the present invention will be set forth in part in the description that follows, and in part will be obvious from that description or can be learned by practice of the invention. The advantages of the invention can be realized and obtained by the apparatus particularly pointed out in the appended claims.
The present invention overcomes the problems of prior art shock tube connector systems and accomplishes its purpose by providing a mechanism to secure up to four shock tubes in each of two parallel rows positioned on laterally opposite sides of the explosive end of a detonator so that the longitudinal axes of the shock tubes are substantially orthogonal to the longitudinal axis of the detonator. The explosive end of the detonator preferably has a reduced diameter and extended length and has an explosive charge distributed longitudinally within it to provide the appropriate energy blast to the rows of shock tubes.
To overcome the problems of the prior art shock tube connector systems, and in accordance with the purpose of the invention, as embodied and broadly described herein, the connector block of this invention is for transmitting a detonation signal to one or more shock tubes from a detonator having a longitudinal axis and an explosive end portion containing an explosive charge and comprises a housing having a first end and a second end and a tube holder connected to the first end of the housing. The housing is adapted to receive a detonator therein with the explosive end of the detonator disposed adjacent the first end of the housing. The tube holder includes at least one engaging slot extending parallel to the longitudinal axis of the detonator and alongside the explosive end of the detonator when the detonator is received in the housing. The engaging slot is adapted to frictionally grip at least four shock tubes alongside the explosive end of the detonator with the longitudinal axes of the shock tubes substantially orthogonal to the longitudinal axis of the detonator.
Preferably, the tube holder includes a base member having one end connected to the first end of the housing with a bore adapted to receive the explosive end of the detonator therein, a cross member connected to the distal end of the base member and extending substantially orthogonally with respect to the longitudinal axis of the detonator, and a pair of engaging flanges depending from the cross member and extending toward the housing on substantially laterally opposite sides of the base member. Each of the engaging flanges is spaced from the base member to define between the respective engaging flange and the base member an engaging slot, and each of the engaging slots is adapted to frictionally grip a plurality of shock tubes alongside the explosive end of the detonator with the longitudinal axes of the shock tubes substantially orthogonal to the longitudinal axis of the detonator.
In another aspect of the invention, the shock tube connector system comprises a substantially cylindrical detonator having a longitudinal axis, a block body receiving the detonator therein, and an end cap. The detonator includes an exterior shell including a cylindrical main section, a cylindrical explosive end portion having a diameter less than the diameter of the main section, and a transition portion connecting the main section and the explosive end portion of the shell. The shell is substantially axisymmetric with respect to the longitudinal axis of the detonator, and the main section has a signal end longitudinally opposite the explosive end portion. An explosive charge is contained within the explosive end portion of the shell and is distributed along the longitudinal length of the explosive end portion. An initiating shock tube is operatively connected to the explosive charge. The initiating shock tube enters the detonator at the signal end of the main section of the shell and is adapted to transmit an ignition signal to the detonator causing the explosive charge to ignite. The block body includes a housing having a first end and a second end, with the main section of the detonator being received within the housing and the explosive end portion of the detonator extending beyond the first end of the housing. A tube holder is connected to the first end of the housing. The tube holder includes a base member having a bore, with the explosive end portion of the detonator being received within the bore. The tube holder includes at least one engaging flange spaced from the base member, with the base member and the engaging flange defining therebetween an engaging slot extending parallel to the longitudinal axis of the detonator and alongside the explosive end of the detonator received in the bore. The engaging slot is adapted to frictionally grip a plurality of shock tubes alongside the explosive end of the detonator with the longitudinal axes of the shock tubes substantially orthogonal to the longitudinal axis of the detonator. The end cap is connected to the second end of the housing and secures the detonator within the block body.
The accompanying drawings, which are incorporated in and which constitute a part of this specification, illustrate at least one embodiment of the invention and, together with the description, explain the principles of the invention.